Tapeinostemon

  • Authority

    Maguire, Bassett. 1978. The botany of the Guayana Highland--part XI. Mem. New York Bot. Gard. 32: 1-391.

  • Family

    Gentianaceae

  • Scientific Name

    Tapeinostemon

  • Description

    Genus Description - Inflorescence terminal or axillary, pedunculate in lax dichasial panicles or, in one instance, capitate; flowers small, 5-merous; calyx deeply 5-partite, persistent; corollas tubular or somewhat flaring; stamens 5, inserted ca midway on corolla tube, filaments short; anthers sagittate or subcordate; pollen grains single, sphaeroidal or somewhat oblong, tricolporate, reticulate; ovary 2-locular, placentation intraflexed, styles persistent or variously deciduous, stigmas 2; seed numerous, small, testa areolate. Ample annual herbs, to 2 m high.

  • Discussion

    6. Tapeinostemon Bentham, Kew Jour. Bot. 6: 194. Jul 1854. Stahelia Jonker, Rec. Trav. Bot. Neeri. 34: 494, fig 7. 1 Type. Tapeinostemon spenneroides Bentham. Tapeinostemon is a small genus of six species, as interpreted here, with the center of distribution in Guayana. Two new proposals are made herein. Distinctions within the genus are somewhat fluid, suggesting an incomplete sorting out. Since the initial presentation by Bentham (1854), taxonomically the genus has been reviewed chiefly by Progel (1865) in his treatment of the family in Flora Brasiliensis, and by Steyermark (1951). Jonker (1937, 1948) sought to establish Stahelia as a separate genus, but our study does not support the segregation. Steyermark's (1951) review of the genus was made with competent understanding of critical flower and fruit morphology. The present report is largely in agreement with Steyermark's views. The chief bases for the estabhshment of Stahelia were Jonker's own observations and his acceptance of Bentham's original judgment in considering the Stigmas to be sessile or essentially so in Tapeinostemon capitatum and T. spenneroides—this despite the explicit statement and drawing to the contrary in Progel's (1865) treatment ofthe genus. Steyermark's observations of a ". . . two-lobed stigmas, and a more or less evident style which eventually becomes deciduous" are essentially accurate. PoUens of Tapeinostemon consistently are monads, commonly sphaeroidal, tricolporate and reticulate. In general they conform to NUsson's ''Glabra-type'' (1970).